Update User Profile field

I am fetching two value from select boxes from user at the time of registration. Let suppose "Domain" and "Profile". I have set multiple option in that like below.


  • Computer
  • Food
  • Government


  • Solution Architect
  • Infra Architect
  • Developer

I have 1000 of users with "Solution Architect" in there profile. Now i want to update all the user's profile from "Solution Architect" to "Architect". How can I achieve it. Please suggest.